type of enzyme inadequacy and glycoprotein accumulated. Cleidocranial dysostosis Cleidocranial dysostosis is a general skeletal condition named for the collarbone (cleido-) and cranium deformities which people with it often have. Common features include: Partly or completely missing collarbones. A soft spot or larger soft area in the top of the head where the fontanelle failed to close. Bones and joints are underdeveloped. The permanent teeth include supernumerary teeth. Permanent teeth not erupting Bossing (bulging) of the forehead. Hypertelorism Fibrous dysplasia Fibrous dysplasia causes bone thinning and growths or lesions in one or more bones of the human body. These lesions are tumor-like growths that consist of replacement of the medullary bone with fibrous tissue, causing the expansion and weakening of the areas of bone involved. Especially when involving the skull or facial bones, the lesions can cause externally visible deformities. The skull is often, but not necessarily, affected, and any other bones can be involved. Langer–Giedion syndrome Langer–Giedion syndrome is a very rare genetic disorder caused by a deletion of chromosomal material. Diagnosis is usually made at birth or in early childhood. The features associated with this condition include mild to moderate learning difficulties, short stature, unique facial features, small head and skeletal abnormalities including bony growths projecting from the surfaces of bones. Maffucci syndrome Maffucci syndrome is a sporadic disease characterized by the presence of multiple enchondromas associated with multiple simple or cavernous soft tissue hemangiomas. Also lymphangiomas may be apparent. Patients are normal at birth and the syndrome manifests during childhood and puberty. The enchondromas affect the extremities and their distribution is asymmetrical. Osteosclerosis Osteosclerosis, an elevation in bone density, is normally detected on an X-ray as an area of whiteness, and is where the bone density has significantly increased. Localized osteosclerosis can be caused by injuries that compress the bone, by osteoarthritis, and osteoma. Other Deformity type Erlenmeyer flask gives a distal femur similar to an Erlenmeyer flask. It may result from Gaucher disease. Kashin–Beck disease Melnick–Needles syndrome Ovine chondrodysplasia Familial osteodysplasia, Anderson type Diagnosis The diagnosis is mainly based upon delineating the specific clinical and radiographic pattern of skeletal involvement. However, the different types of skeletal dysplasia can overlap considerably in their clinical presentation. Molecular or genetic analysis may be required to resolve diagnostic difficulties. Molecular analysis is also of importance to the phenotype genotype correlations and to disease classifications. Differential diagnosis Juvenile idiopathic arthritis may